Recess gate process control by using 3D SCD in 3xm vertical DRAM

Kuo, M. X.; Wu, Sheng-Hung; Lan, Tian; Chang, Shuang Hsun; Wang, Elvis; Chouaib, Houssam; Cheng, Harvey; Zhao, Qiang

doi:10.1117/12.916143

Cited by 9 publications

(7 citation statements)

References 6 publications

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“…5 to 8 for the SE measurement principle and application examples 5 – 8 The SE signals were also collected in two perpendicular wafer-rotation angles defined by the MHs X and Y pitch directions with respect to SE incident planes. See Fig.…”

Section: Wafer Measurements and Analysesmentioning

confidence: 99%

Flash memory hole etch profile monitoring using x-ray and optical scatterometry

Sorkhabi

Zhang

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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Memory hole (MH) etching may be one of the most critical and challenging processes in three-dimensional flash processing and integration. As the holes get deep, hole critical dimensions (CDs) can vary significantly during the top-down etch processing, the hole shape can deviate from a round hole, and the centerline of the hole can deviate from a vertical line. These and other complex behaviors depend on not only the process conditions (chemistry, plasma power, bias, temperature, etc.) but also the process chamber history [e.g., radio frequency (RF) hours from preventative maintenance] and how the process chambers are conditioned. In addition, the etch behavior depends on the tier thickness (ONON or OPOP), materials, deposition conditions, and overall wafer topography and shapes. The etch behavior is further related to the die positions on the wafer (center or middle versus edge dies) and the position in the memory cell (close to the edge of the cell or near the center of the cell). To monitor and control the etch behavior, many metrology methods have been developed; these include the etch-back top-view scanning electron microscopy (SEM), tilt SEM, transmission electron microscopy (TEM), and high voltage scanning electron microscopy (HVSEM). These methods are time consuming, and some are destructive, but they have been deemed the ground truth for determining variations in MH etch processes. We report a methodology that combines optical scatterometry (SCD) and small-angle x-ray scatterometry measurements to provide reliable CD profile measurements while meeting the fast-turnaround sampling requirements of high-volume manufacturing.

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Section: Wafer Measurements and Analysesmentioning

confidence: 99%

Flash memory hole etch profile monitoring using x-ray and optical scatterometry

Sorkhabi

Zhang

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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“…Figure 1. Two typical overlay process control loops: ADI metrology and ACI metrology Spectroscopic ellipsometry (SE) has been used for CD (critical dimension) metrology for many years as a robust overlay metrology solution due to the Mueller matrix signal from SE's sensitivity to overlay error metrology [1][2][3][4][5][6][7]. Furthermore, as an optical solution, SE offers the advantages of relatively high throughput and precision versus other overlay metrology solutions, such as CD-SEM.…”

Section: Introductionmentioning

confidence: 99%

Optical in die NZO benefit for DRAM manufacturing

Yeh,

Tsai,

Chu

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

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Today, with the accelerating complexity of nanoelectronics for memory applications, in-die overlay metrology has required much tighter control. A typical in-device overlay control strategy utilizes high-voltage SEM metrology across several key layers, but lot and wafer sampling is limited due to low system throughput. Our objective is to find a faster, more robust, and more efficient optical metrology solution that can produce the same in-die overlay results vs. SEM. In this work, we create a novel solution using the KLA SpectraShape™ 11k dimensional metrology system to demonstrate improved nonzero overlay (NZO) control that meets the tighter overlay budget requirement.We combined the spectroscopic Mueller matrix of SpectraShape 11k and the machine learning algorithm of TurboShape™ modeling software. Both real spectra collected by SpectraShape 11k and theoretical spectra generated from the scatterometry model are trained against their corresponding SEM reference and synthetic reference data respectively to predict the overlay value. Accurate and robust optical in-device overlay results are proven with a high correlation to the HV-SEM data. In addition, the SpectraShape 11k in-device overlay is equipped with a few key performance indicators (KPIs) including CIndex™ and CD profile, which are designed to flag process excursions in an HVM environment. Good agreement is observed between the KPIs and overlay delta to HV-SEM. Finally, the 4x-8x throughput advantage of optical metrology in-device overlay vs. SEM in-device overlay allows users to set more dense wafer measurements by lot or dense site measurements by wafer, enabling better lot-to-lot or wafer-to-wafer NZO control.

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“…Figure 1. Overlay process control loop including after-develop inspection (ADI) and after-etching inspection (ACI) Spectroscopic ellipsometry (SE) has been used for CD (critical dimension) metrology for many years as a robust overlay metrology solution [1][2][3][4][5][6]. Furthermore, as an optical solution, SE offers the advantages of relatively high throughput and precision vs. other overlay metrology solutions, such as CD-SEM.…”

Section: Introductionmentioning

confidence: 99%

Scatterometry and machine learning for in-die overlay solution

Yeh¹,

Chouaib²

2023

Metrology, Inspection, and Process Control XXXVII

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Advanced technology nodes require tighter lithography overlay specifications with higher throughput and lower cost of ownership. Today, with the accelerating complexity of nanoelectronics for memory applications, an increased emphasis is placed on controlling the on-product overlay (OPO) budget. Consequently, accurate in-die overlay measurements play a critical role after the etching process (ACI) for which it can better reflect the actual product overlay. Here we propose a solution with the combined spectroscopic full Mueller matrix, measured with the KLA next-generation SpectraShape™ dimensional metrology system and a physics-based machine learning algorithm. Both real spectra collected by the SpectraShape and theoretical spectra generated from the scatterometry model are trained against their corresponding ground truth reference and synthetic reference data respectively to predict overlay. Theoretical and experimental results show that the Mueller elements are sensitive to very small changes in the overlay parameters which can enable inline, high-throughput overlay metrology. Accuracy, robustness, and precision on massive datasets using design of experiments (DOE) wafers are presented and discussed. Moreover, the measurement reliability is assessed with a key performance indicator (KPI), designed to flag a process excursion in a high-volume manufacturing (HVM) environment. Good agreement is observed between the KPI and the actual model accuracy.

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Recess gate process control by using 3D SCD in 3xm vertical DRAM

Cited by 9 publications

References 6 publications

Flash memory hole etch profile monitoring using x-ray and optical scatterometry

Flash memory hole etch profile monitoring using x-ray and optical scatterometry

Optical in die NZO benefit for DRAM manufacturing

Scatterometry and machine learning for in-die overlay solution

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